For all those putting up theoretical reasons not to make any changes to the "one person in the cockpit" situation, two facts:
1. All 6 of the most recent pilot killing / suicides took place while one person was alone in the cockpit.
2. In the same time period not a single pilot killing / suicide has taken place on a US airline where "one person in the cockpit" is not permitted at any time.
Adopting a policy that has clearly worked is a sensible, measured and appropriate response to this, the sixth mass pilot killing since 1994 and the third in three years.